Thats because Eric is doing Jessicas stuff for her. If it doesn't require sleeping then she doesn't know what to do! Jameka talked to Dick and obviously shes not going to "try" and get his vote and she knows that the Donatos vote the same way so what is the point, she knows she isn't going to have Erics vote. So in her mind its set in stone to be 3-0. Jessica did have doubt BUT Eric convinced her that noooooooooo they weren't going to do that. They knew that Zachs target was Jameka. They know that if htey wanted Jessica/Eric to go home then Daniele would have saved Jameka with the POV and put them up against each other.
She also was mad while packing because she really does not want to, and was slamming stuff in the suitcase.